Geographical Distribution and Pattern of Pesticides in Danish Drinking Water 2002–2018: Reducing Data Complexity

Abstract

Pesticides are a large and heterogenous group of chemicals with a complex geographic distribution in the environment. The purpose of this study was to explore the geographic distribution of pesticides in Danish drinking water and identify potential patterns in the grouping of pesticides. Our data included 899,169 analyses of 167 pesticides and metabolites, of which 55 were identified above the detection limit. Pesticide patterns were defined by (1) pesticide groups based on chemical structure and pesticide–metabolite relations and (2) an exploratory factor analysis identifying underlying patterns of related pesticides within waterworks. The geographic distribution was evaluated by mapping the pesticide categories for groups and factor components, namely those detected, quantified, above quality standards, and not analysed. We identified five and seven factor components for the periods 2002–2011 and 2012–2018, respectively. In total, 16 pesticide groups were identified, of which six were representative in space and time with regards to the number of waterworks and analyses, namely benzothiazinone, benzonitriles, organophosphates, phenoxy herbicides, triazines, and triazinones. Pesticide mapping identified areas where multiple pesticides were detected, indicating areas with a higher pesticide burden. The results contribute to a better understanding of the pesticide pattern in Danish drinking water and may contribute to exposure assessments for future epidemiological studies.

Unravelling the Occurrence of Trace Contaminants in Surface Waters Using Semi-Quantitative Suspected Non-Target Screening Analyses

“…The majority of confirmed compounds were well-known trace organic contaminants found in European surface waters (Silva et al, 2011;Singh et al, 2021;Skaarup et al, 2022). Some examples are pharmaceutical residues such as venlafaxine, diclofenac, and carbamazepine; pesticides such as diflufenican, fluopyram, and prosulfocarb, and other compounds such as citroflex 2, sucralose, and triethyl phosphate.…”

“…Some pesticides, e.g. bentazone, 2-methyl-4-chlorophenoxyacetic acid (MCPA), mecoprop, atrazine, and dinoseb, restricted or not approved for use in Denmark or the EU (Skaarup et al, 2022) were among the detects. This clearly depicts the incessant contamination of surface water through the emission of pesticides with long lifetimessome (so-called 'legacy') pesticides can persist or remain in the environment, e.g.…”

National Assessment of Long-Term Groundwater Response to Pesticide Regulation

“…Over the last two decades, regulations have been implemented in the European Union (EU) and at national levels in Europe to alleviate the contamination of groundwater resources caused by pesticide use. − However, a recent status assessment of EU water bodies showed that 6.5% of the area of groundwater bodies were failing the good chemical status as defined in the EU Water Framework Directive due to pesticides . In Denmark, where groundwater is the sole source of drinking water, this was the case for 7.5% of the total 2050 groundwater bodies representing 17% of the total volume of the Danish groundwater bodies, and pesticides and their degradation products are still found in drinking water. , …”

“…3 In Denmark, where groundwater is the sole source of drinking water, this was the case for 7.5% of the total 2050 groundwater bodies representing 17% of the total volume of the Danish groundwater bodies, 4 and pesticides and their degradation products are still found in drinking water. 5,6 Long legacy effects of persistent pesticides and degradation products in groundwater after application bans are explained by a time delay caused by (1) hydrological transport from the topsoil to the underlying aquifers and (2) compound-specific retardation during the hydrological transport. After mobilization from the topsoil, the pesticides and their degradation products are transported to aquifers mainly as solutes via water.…”

“…3 In Denmark, where groundwater is the sole source of drinking water, this was the case for 7.5% of the total 2050 groundwater bodies representing 17% of the total volume of the Danish groundwater bodies, 4 and pesticides and their degradation products are still found in drinking water. 5 , 6 …”